U.S. Pat. No. 5,264,125, Process for Manufacturing Continuous Supported Ion Selective Membranes Using Non-Polymerizable High Boiling Point Solvents, describes a continuous process for making a supported ion exchange membrane. The process comprises forming a continuous sandwich of a substrate and a pliable film on each face of the substrate. The films extend beyond the side edges of the substrate. The edges of the films are sealed together to form a pocket containing the substrate. Subsequently, the sandwich is pulled between a pair of squeeze rolls. A liquid is added to the pocket above the squeeze rolls to form a pool of the liquid above the squeeze rolls and between the films. The liquid wets the substrate and fills apertures in the substrate before the sandwich passes through the squeeze rolls. From the squeeze rolls, the sandwich passes through a set of means, for example heaters, for curing the liquid. Polymerizable components in the liquid are polymerized thereby forming a reinforced polymer sheet. The sandwich continues through a set of knives which remove the seals at the edges of the sandwich and through a pair of rollers which remove the films from the polymer sheet. The polymer sheet is then ready for use as an ion exchange membrane.
In the process described above, the rate of production is a function of the required curing time and the length of the curing region. Since it is costly to increase the length of the curing region, some efforts have been made to increase production rates by providing faster reactions, for example by using more active catalysts or higher curing temperatures to increase reaction rates.